The present invention relates broadly to vehicular transmissions. In general, the present invention relates to two-mode, compound-split, vehicular transmissions. More particularly, the present invention relates to two-mode, compound-split, vehicular transmissions that utilize supplemental power receiving/delivery units that derive their power from an on-board source of electrical energy. Specifically, the present invention relates to a two-mode, compound-split, electro-mechanical, vehicular transmission wherein the interactive planetary gear subsets are operatively connected to an engine and two power receiving/delivery unitsxe2x80x94motor/generators, as shownxe2x80x94that may be annularly configured to minimize the overall envelope within which the transmission is contained, but whereas such concentricity may be desirable to conserve space, it is not critical to the operation of the invention. A power delivering shaft extends axially within the transmission to deliver driving power to left and right output planetary gear subsets from which respective left and right output shafts project to drive the track, or even the wheels, that propel the vehicle.
The purpose of a vehicular transmission is to provide a neutral, at least one reverse and one or more forward driving ranges that impart power from an engine, and/or other power sources, to the drive members which deliver the tractive effort from the vehicle to the terrain over which the vehicle is being driven.
As explained in detail in U.S. Pat. No. 5,931,757 issued on Aug. 8, 1999, and assigned to General Motors Corporation, the challenge is to provide a power system that will operate at high efficiencies over a wide variety of operating conditions. Desirable electric variable transmissions should leverage not only the benefits of a series, hybrid transmission for desirable low-average power duty cyclesxe2x80x94i.e.: low speed start/stop duty cyclesxe2x80x94but also the benefits of a parallel hybrid transmission for high-average output power, high speed duty cycles.
To this point in time, a highly respected hybrid transmission for a tracklaying vehicle has been a four-mode, input-split, parallel transmission that is the subject of U.S. Pat. No. 5,571,058 which issued on Nov. 5, 1996, and was also assigned to General Motors Corporation.
By way of background, in a parallel arrangement the power supplied by the engine and the power supplied by the source of electrical energy are independently connected to the drive members. Perfecting a concept wherein multiple modes, or gear trains, are available for synchronous selection by the on-board computer to transmit power from the engine and/or selected supplemental power receiving/delivery units, such as motor/generators, to the output shaft results in a hybrid transmission having an extremely wide range of applications, the many beneficial results of which may be achieved by the use of a variable, two-mode, input-split, electro-mechanical transmission.
However, and particularly for use in a military track vehicle, the electrical auxiliary loads (also commonly referred to as the xe2x80x9chotelxe2x80x9d loads) can require a high percentage of the engine power. Hence, if one additionally desires to provide for xe2x80x9csilent operationxe2x80x9d of the vehicle under certain conditions, the electrical receiving/delivery units must transfer power from and, if batteries are employed as the source of electrical power, to the source of electrical energy to power not only the means to move the vehicle but also the power required to satisfy the hotel loads. If motor/generators are employed the resulting power required properly to operate such a vehicle precludes a reduction in the size of the motor/generators. A two-mode, compound-split transmission has been an excellent choice for development with many commercial vehicles, particularly inasmuch as such a transmission does provide a mechanical point in the first forward mode of operation, and that helps meet the cooling requirements at low vehicle speeds. However, that transmissions used in commercial vehicles typically do not have an independent reverse mode, nor are the versions of transmissions adapted for commercial vehicles readily capable of providing silent operation for the vehicle in which they are used.
Nevertheless, by incorporating the present invention in a two-mode, compound-split, electro-mechanical transmission it becomes a very attractive package, particularly for track-laying military vehicles, even with all their attendant operational requirements.
It is, therefore, one primary aspect of the present invention to provide a new and novel, two-mode, compound-split, electro-mechanical transmission that is particularly suited for driving track-laying vehicles.
It is another aspect of the present invention to provide a novel, two-mode, compound-split, electro-mechanical transmission, as above, wherein the transmission utilizes separate clutches for selecting the reverse and first mode forward ranges.
It is a further aspect of the present invention to provide a novel, two-mode, compound-split, electro-mechanical transmission, as above, wherein the transmission may employ either concentric or countershaft power receiving/delivery units such as motor/generators.
It is a still further aspect of the present invention to provide a novel, two-mode, compound-split, electro-mechanical transmission, as above, wherein the steering motor does not need its own generator.
It is yet another aspect of the present invention to provide a novel, two-mode, compound-split, electro-mechanical transmission, as above, wherein the transmission employs a disconnect clutch to permit stealth operation with the engine off and disconnected from the transmission so that operational power is provided solely from the source of electrical power through the supplemental power receiving/delivery units.
It is a still further aspect of the present invention to provide a novel, two-mode, compound-split, electro-mechanical transmission, as above, wherein the transmission provides a mechanical point in both the forward first mode range and the reverse range to assist with the low speed cooling requirements.
These and other aspects of the invention, as well as the advantages thereof over existing and prior art forms, which will be apparent in view of the following detailed specification, are accomplished by means hereinafter described and claimed.
By way of a general introductory description, a two-mode, compound-split, electro-mechanical transmission embodying the concepts of the present invention is particularly adapted for use with track-laying vehicles. The transmission utilizes a plurality of planetary gear subsets, and each planetary gear subset has a plurality of components in the nature of an inner, sun gear, an outer, ring gear circumscribing said inner, sun gear and a plurality of planet gears rotatably mounted on a carrier such that the planet gears each simultaneously mesh with the inner, sun gear and the outer, ring gear of the planetary gear subset in which that carrier is incorporated.
The transmission receives its operating power from several sources. There is a prime mover power source in the nature of an internal combustion engine. There is a source for storing and providing electrical energy, and there are first and second power receiving and delivery units. There is a steering motor and a steering mechanism for operating the steering motor. The source for storing and providing electrical energy, the steering mechanism, the steering motor and the first and second power receiving and delivery units communicate with each other by virtue of an electrical control unit.
The planetary gear subsets include left and right output planetary gear subsets, each of which present an output shaft. The left and right planetary gear subsets are connected to each other by a retro-rotational gear and shaft assembly so that the left and right output shafts may selectively rotate in the same or in opposite directions and at the same or at different speeds, one with respect to the other.
To acquaint persons skilled in the arts most closely related to the present invention, one representative preferred embodiment of a two-mode, compound-split, electro-mechanical transmission now contemplated for putting the invention into practice is described herein by, and with reference to, the annexed drawings that form a part of the specification.
It must be understood that the aforesaid exemplary form of a preferred two-mode, compound-split, electro-mechanical transmission is described in detail without attempting to show all of the various forms and modifications of the essential elements in which the invention might be embodied.
As such, the embodiment shown and described herein is only illustrative, and as will become apparent to those skilled in these arts can be modified in numerous ways within the spirit and scope of the invention; the invention being measured by the appended claims and not by the details of the specification.